Conveyer-belt.



T. ROBINS.

GONVEYER BELT.

APPLICATION I'ILED NOV.17, 190s.

1 31 Patented Jan.10,1911.

THOMAS ROBINS, OF NEW YORK, N. Y.

'coNvEYEn-BELT.

Specification of Letters Patent.

Patented Jan. 10, 1911.

Application filed November 17, 1906. Serial No. 343,933.

To all whom it may concern:

Be it known that I, THOMAS ROBINS, a citizen of the United States,residing in the city, county, and State of New York, have invented a newand useful Improvement in conveyer-Belts, of which the following is aspecification.

This invention relates to conveyer belts, and it has for its primaryobject the provision of a conveyer belt characterized by greaterdurability than conveyer belts hitherto produced which may bemanufactured at substantially the same or less cost than' conveyer beltsas at present constructed.

Other objects of the invention will appear in the course of thefollowing description, in which reference is had to the accompanyingdrawings, wherein I have illustrated several forms of belt embodying thepresent invention.

In the construction of conveyer belts the practice now almost invariablyfollowed is to build up the body portion of the belt, which is designedto afford the required tensile strength, out of a number of plies oftextile fabric, such as cotton duck, united by interposed layers ofunvulcanized rubber stock rubbed into the fabric by calender rolls.These interposed layers of unvulcanized rubber stock, or friction, areusually applied to the fabric in the plastic or solid state and do notpenetrate the fabric so as to thoroughly coat all the fibers of which itis composed. On the contrary, only the superficial fibers of each ply offabric come into contact with the rubber friction and itis comparativelyeasy to separate the alternate layers of rubber and fabric which enterinto the body of the belt.

On the outer surfaces of the body of the conveyer belt formed in themanner above mentioned, a cover of some suitable rubber compound isapplied, this cover being ordinarily considerably thicker on one surfaceof the belt than the other, as only one surface of the conveyer belt isordinarily employed as a carrying surface. After the belt body has beenbuilt up and the cover of unvulcanized rubber stock applied thereto, therubber in both the cover and the layers of friction in the body of thebelt is vulcanized by subjecting the belt to a vulcanizing heat in apress by which the entire belt structure is subjected to any desireddegree of pressure during the vulcanizing operation. The sulfur or othervulcanizing agent is of course incorporated with the rubber used in theconstruction of the belt before the belt is built up.

Belts constructed in the manner just described are commonly known asrubber belts, and they manifest certain undesirable characteristics whensubjected to heavy service. Owing to the character of the materialstransported by conveyer belts and the conditions under which the beltsare used, the cover of the belt is apt to become abraded or cut so as toexpose the fabric employed in the body of the belt, and moisture is soallowed to come into contact with the fabric through these abrasions orcuts. As the fibers of the fabric in each ply of the belt arecoated withrubber only at the surface, and as the rubber has not been found inpractice to penetrate between the fibers of each thread even thoughoriginally applied in very plasticor cement-like condition, any moisturewhich reaches one of the plies of fabric in the belt body is absorbed bythe fabric and disseminated through itby capillary action for aconsiderable dis tance from the abrasion or cut through which themoisture has penetrated to the fabric. The action of moisture upon thecotton fiber, which is almost invariably used in the construction ofconveyer belts, causes rapid deterioration of the fiber and soonpractically destroys the fabric of any ply of the belt affected for aconsiderable distance around the cut or abrasion through which waterpenetrates through the cover of the belt. As a result of thisdestruction of a portion of the layer of fabric immediately underlyingthe cover of the belt, a blister is formed in the belt in the localityaffected and the portion of the cover overlying the blister is very aptto be torn loose, particularly when the belt is subjected to heavyservice. As a further consequence of the action of water upon the fabricof a conveyer belt as at present constructed, several plies of fabricmay be affected by water, because it not infrequently happens that theinterposed layers of rubber friction are not impervious to water and thewater may penetrate through several plies when there is a cut orabrasion of the belt cover. When this takes place, a section of the beltbecomes \Vhen the character of the material handled and the conditionsunder which the belt is operated are not such as to cause thedeterioration above mentioned, the cover of the belt may gradually wearaway without serious injury to the body of the belt, and in that eventit is desirable to replace the worn cover by a new one; but it ispractically impossible to replace the cover of an old conveyer belt ofthe resent construction eco nomically or effectively. The worn portionof the cover can not be readil detached and it is not ordinarilypractica 1e to apply a new cover over the old and worn one and obtainsuch union of the new cover with the belt that it will adhere firmlythroughout under the strains of ordinary service. Generally speaking,therefore, the life of a conveyer belt as at present constructed is nogreater than the life of the cover, and when used with highly abrasivematerial and in the presence of much moisture, as when handling wetstone or ore, the body of the belt may become practically worthlessbefore the cover is worn out.

The improved conveyer belt which forms the present invention is designedto eliminate the undesirable characteristics of conveyer belts of theusual construction which have been above pointed out. The improvedconveyer belt consists of a body composed of a compound of gutta perchaor equivalent substance, referabl with strengthenin material em edded terein, and a cover vulcanized rubber compound.

In the construction of the body I ordinarily employ a suitable number ofplies of textile fabric thoroughl saturated with the compound of guttaperc a or equivalent substance balata probably being the most desirablesubstance to use and the compound being applied in liquid condition tothe duck so that it may penetrate between the fibers of a strand as wellas between strands of the fabric. The number of plies of fabric employedin the body of the belt will vary, of course, with the size and strengthof belt desired, but each ply is thoroug ly saturated with a compound ofgutta percha or equivalent material, such as balata, and ordinarily acompound containing both of these ingredients will be employed and theterm gutta percha as hereinafter employed is intended not only toinclude the true gutta percha but balata, or a mixture of both or eitherwith other materials which do not destroy the characteristic propertiesthereof.

In the construction of a conveyer belt according to the presentinvention, the plies of fabric for the body of the belt are coated Iwith gutta percha in a semi-fluid condition,

pound entirely through the several plies of fabric and completelysaturate them. The pressure is preferably a rolling pressure and thebelt body produced may be described as a mass of gutta perchapenetrating or impregnating the textile fabric embedded therein. Thisbelt body is completely waterproof and if an incislon is made thereintoand water introduced into it, the water will not extend through the liesof fabric adjacent to the incision, pro ably because each fiber of thefabric is completely coatedwith the gutta percha compound and thecapillarity of the fabric has been wholly eliminated. On the belt bodyformed of fabric and gutta percha compound I apply a cover of vulcanizedrubber compound which is secured to the belt body by a gutta perchacement and which may be held in place by additional fastening means, ifdesired. This cover may be applied to one or both surfaces of the beltand may be extended over the edges of the belt body if desired, but,owing to the thoroughly water-proof character of the body of the belt,the extension of the cover over the edges is not necessary, as inconveyer belts of the type now commonly emlployed.

' n the accompanying drawings I have shown three types of belt embodyingthe present invention.

Figure 1 is a view in transverse section of a belt having the edges ofthe cover protected by plies of fabric from the belt body which overliethe edges of the cover. Fig. 2 is a transverse sectional view of a beltin which both the cover and the body are of uniform thickness throughoutand the cover is simply cemented upon one surface of the belt body. Fig.3 is a transverse sectional View of a belt in which the cover isprotected at the margins by overlying plies of the fabric from the beltbody and rivets are provided adjacent to the margins of the belt toassist in securing the cover to the body of the belt.

Referrin now to the drawings by the reference 0 aracters, the numeral 1is used to designate a ply of cotton-duck or other textile fabric, andthe numeral 2 designates the protective coating of gutta percha compoundapplied to each ply of duck and forming the layers of gutta perchainterposed between the plies of fabric in the belt body. In the drawingthe plies of fabric are shown in White and the interposed layers andcoatings of gutta percha compound are indicated by black lines.

In Fig. 1 the body A of the belt is shown as made up of a plurality ofplies of fabric and interposed layers of gutta percha compound, the twoplies of fabric at the under surface of the belt body being carriedaround are then superposed and subjected to pres- .the marginal portionsof the cover B of the sure sufficient to force the gutta percha combeltso as to overlie it. The cover B is preferably thickest in its middleportion, where most of the wear is received, and thinnest at themarginal portions, which extend between the main portions of the beltbody and the overlying plies of fabric. The cover is cemented directlyupon the main portion of the belt body entirely across the under surfaceof the cover and the overlying portions of fabric are also cemented onthe outer surface of the cover, a gutta percha cement being usedthroughout.

The belt shown in Fig. 2 is of the simplest possible construction, thebelt body A being composed of the same number of plies of fabricthroughout its entire width and the cover B being a single layer ofrubber compound of uniform thickness throughout its entire width.

The belt illustrated in Fig. 3 is similar in some respects to thatillustrated in Fig. 1. The belt body A has the two plies of fabric atthe under surface extended so as to pass around the edges of the coverB" upon the carrying surface of which they are secured both by cementand by rivets 3 passing entirely through the belt. Except near themargins, where the cover underlies the extended plies of fabric from thebody of the belt, it is of uniform thickness throughout its entirewidth.

All three types of belt illustrated in the drawings have covers whichare readily replaceable when injured. This replaceability of the meltcover results from the ease with which a gutta percha cement may besoftened. While the rubber cover is held on the belt body at ordinarytemperatures with greater tenacity by gutta percha cement than whenvulcanized directly to the fabric, as in the ordinary type of conveyerbelt, gutta percha cement may be so softened when heated to a moderatetemperature that an old cover may be easily stripped off the belt bodyand a new cover applied. The replacement of the cover of the belt shownin Fig. 3 would, of course, be more difiicult than the replacement ofthe cover in either of the other two types of belt, but the removal ofthe rivets shown in Fig. 8 is comparatively easy, and after the rivetshave been removed the overlying plies of fabric can be quickly detachedfrom the belt cover by first heating the belt to the required degree,and then the cover itself can be easily stripped off the belt body.

It will be understood that as gutta percha or balata for the body of thebelt can be rendered as fluid as required by the usual volatilesolvents, with or without heat, no difliculty is encountered incompletely saturating the duck fabric and thereby producing a belt bodythat is substantially non-capillary. Furthermore, as the duck has notbeen subjected to vulcanizing temperature, injury to the cotton fiber byvulcanizing heat is obviated. When the vulcanized rubber cover has beencemented to the body of the belt, the finished belt will possess greattoughness in wear, resistance to deterioration from moisture, and otherdesirable qualities.

As compared with rubber belts consisting of the same number of plies offabric and having belt bodies of the same thickness, belts constructedaccording to the present invention are characterized by considerablygreater tensile strength, because the interposed layers of gutta perchacompound are somewhat thinner than the layers of rubber frictionrequired in the ordinary belts and heavier weight fabric may be employedin producing a belt of given thickness and having a certain number ofplies. Moreover, owing to the enetrating power of the gutta percha or baata as compared with that of rubber, I am able to use more closely wovenand consequently stronger duck and I thus obtain a further increase ofstrength. F urthermore, as gutta percha has a much greater resistance tostretching strains than rubber compounds, a belt constructed accordingto the present invention shows less elongation under a given strain thana rubber belt of similar dimensions.

In the several forms of belt illustrated in the drawings, the cover ofvlucanized rubber compound is shown as extending entirely across thecarrying surface of the belt, as usual in conveyer belts. It is obvious,however, that it is not essential that the cover be extended over theentire carrying surface and, especially in belts upon which the wear islimited to the middle portion of the carrying surface, the ortions ofthe cover adja cent to the margins of the belt may be dispensed with andthe cost of the belt lessened without a substantial diminution of itsstrength and durability.

' Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A conveyer belt having a body composed of a plurality of plies oftextile fabric and interposed layers of a gutta percha compoundpenetrating not only between the strands but between the fibers of thestrands and rendering them non-capillary, and having a cover composed ofa vulcanized rubber compound.

2. A conveyer belt having a body composed of a plurality of plies oftextile material and a gutta percha compound forming inter osed layersbetween said plies and thoroughly saturating said plies, and having acover composed of a vulcanized rubber compound.

3. A conveyer belt having a body portion composed of a plurality ofplies of textile fabric united and saturated by a gutta percha compoundand having a cover composed of a vulcanized rubber compound and sebodyof the belt being extended to overlie 10 cured to said body by means of.gutta percha the edge portions of the cover.

cement. In testimony whereof, I have signed my 4. A oonvcyer belt comrising a body orname in the presence of two Witnesses. 5 tion and acover of ru ber compoun or THOMAS ROBINS other resilient material, saidbod portion being composed of a plurality o plies of Witnesses:

textile fabric united b a Water-proof ad- Rosoon L. PETERSON, hesivecompound, certain of the plies in the BAXTER MORTON.

